Intro

When using mochaHooks in watch mode, it seems that something gets in the way if you have module variables when reloading, making those lose any changes (e.g. storing values on their properties) on watch reloads. Behaviour is fine on first run.

a.js keeps an instance inside itself of A. From the beforeEach() hook (at hooks.js), we store some strings into that a. test/failing.test.js relies on those populated items (accessed via an instance of B, which pulls a), meanwhile test/working.test.js contains its own beforeEach() hook, which makes it work all times.

main.js is present just to showcase a single-file all logic together example, can be dismissed.

STR

1. Run

./node_modules/mocha/bin/mocha.js --watch

On first run, all tests will pass:

  Failing on watch reload
mochaHooks beforeEach(): [ 'testItem1', 'testItem2' ]
    ✔ should return two items

  Always working
mochaHooks beforeEach(): [ 'testItem1', 'testItem2' ]
    ✔ should return two items


  2 passing (2ms)

2. Edit any test file, for example adding a new line, and save.

Expected

Both tests still pass when watch mode reloads and re-runs.

Actual

Although mochaHooks' beforeEach() is called and initializes module variable a, when the test runs after a watch reload, a looks as if empty (cached maybe?) and contains no "initialized items".

  Failing on watch reload
mochaHooks beforeEach(): [ 'testItem1', 'testItem2' ]
    1) should return two items

  Always working
mochaHooks beforeEach(): [ 'testItem1', 'testItem2' ]
    ✔ should return two items


  1 passing (13ms)
  1 failing

  1) Failing on watch reload
       should return two items:

      AssertionError [ERR_ASSERTION]: Expected values to be loosely deep-equal:

[]

should loosely deep-equal

[
  'testItem1',
  'testItem2'
]
      + expected - actual

      -[]
      +[
      +  "testItem1"
      +  "testItem2"
      +]

      at Context.<anonymous> (test/failing.test.js:8:12)
      at process.processImmediate (node:internal/timers:478:21)



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